import click
from functools import update_wrapper
from PIL import Image, ImageFilter, ImageEnhance


@click.group(chain=True)
def cli():
    """This script processes a bunch of images through pillow in a unix
    pipe.  One commands feeds into the next.

    Example:

    \b
        imagepipe open -i example01.jpg resize -w 128 display
        imagepipe open -i example02.jpg blur save
    """


@cli.resultcallback()
def process_commands(processors):
    """This result callback is invoked with an iterable of all the chained
    subcommands.  As in this example each subcommand returns a function
    we can chain them together to feed one into the other, similar to how
    a pipe on unix works.
    """
    # Start with an empty iterable.
    stream = ()

    # Pipe it through all stream processors.
    for processor in processors:
        stream = processor(stream)

    # Evaluate the stream and throw away the items.
    for _ in stream:
        pass


def processor(f):
    """Helper decorator to rewrite a function so that it returns another
    function from it.
    """
    def new_func(*args, **kwargs):
        def processor(stream):
            return f(stream, *args, **kwargs)
        return processor
    return update_wrapper(new_func, f)


def generator(f):
    """Similar to the :func:`processor` but passes through old values
    unchanged and does not pass through the values as parameter.
    """
    @processor
    def new_func(stream, *args, **kwargs):
        for item in stream:
            yield item
        for item in f(*args, **kwargs):
            yield item
    return update_wrapper(new_func, f)


def copy_filename(new, old):
    new.filename = old.filename
    return new


@cli.command('open')
@click.option('-i', '--image', 'images', type=click.Path(),
              multiple=True, help='The image file to open.')
@generator
def open_cmd(images):
    """Loads one or multiple images for processing.  The input parameter
    can be specified multiple times to load more than one image.
    """
    for image in images:
        try:
            click.echo('Opening "%s"' % image)
            if image == '-':
                img = Image.open(click.get_binary_stdin())
                img.filename = '-'
            else:
                img = Image.open(image)
            yield img
        except Exception as e:
            click.echo('Could not open image "%s": %s' % (image, e), err=True)


@cli.command('save')
@click.option('--filename', default='processed-%04d.png', type=click.Path(),
              help='The format for the filename.',
              show_default=True)
@processor
def save_cmd(images, filename):
    """Saves all processed images to a series of files."""
    for idx, image in enumerate(images):
        try:
            fn = filename % (idx + 1)
            click.echo('Saving "%s" as "%s"' % (image.filename, fn))
            yield image.save(fn)
        except Exception as e:
            click.echo('Could not save image "%s": %s' %
                       (image.filename, e), err=True)


@cli.command('display')
@processor
def display_cmd(images):
    """Opens all images in an image viewer."""
    for image in images:
        click.echo('Displaying "%s"' % image.filename)
        image.show()
        yield image


@cli.command('resize')
@click.option('-w', '--width', type=int, help='The new width of the image.')
@click.option('-h', '--height', type=int, help='The new height of the image.')
@processor
def resize_cmd(images, width, height):
    """Resizes an image by fitting it into the box without changing
    the aspect ratio.
    """
    for image in images:
        w, h = (width or image.size[0], height or image.size[1])
        click.echo('Resizing "%s" to %dx%d' % (image.filename, w, h))
        image.thumbnail((w, h))
        yield image


@cli.command('crop')
@click.option('-b', '--border', type=int, help='Crop the image from all '
              'sides by this amount.')
@processor
def crop_cmd(images, border):
    """Crops an image from all edges."""
    for image in images:
        box = [0, 0, image.size[0], image.size[1]]

        if border is not None:
            for idx, val in enumerate(box):
                box[idx] = max(0, val - border)
            click.echo('Cropping "%s" by %dpx' % (image.filename, border))
            yield copy_filename(image.crop(box), image)
        else:
            yield image


def convert_rotation(ctx, param, value):
    if value is None:
        return
    value = value.lower()
    if value in ('90', 'r', 'right'):
        return (Image.ROTATE_90, 90)
    if value in ('180', '-180'):
        return (Image.ROTATE_180, 180)
    if value in ('-90', '270', 'l', 'left'):
        return (Image.ROTATE_270, 270)
    raise click.BadParameter('invalid rotation "%s"' % value)


def convert_flip(ctx, param, value):
    if value is None:
        return
    value = value.lower()
    if value in ('lr', 'leftright'):
        return (Image.FLIP_LEFT_RIGHT, 'left to right')
    if value in ('tb', 'topbottom', 'upsidedown', 'ud'):
        return (Image.FLIP_LEFT_RIGHT, 'top to bottom')
    raise click.BadParameter('invalid flip "%s"' % value)


@cli.command('transpose')
@click.option('-r', '--rotate', callback=convert_rotation,
              help='Rotates the image (in degrees)')
@click.option('-f', '--flip', callback=convert_flip,
              help='Flips the image  [LR / TB]')
@processor
def transpose_cmd(images, rotate, flip):
    """Transposes an image by either rotating or flipping it."""
    for image in images:
        if rotate is not None:
            mode, degrees = rotate
            click.echo('Rotate "%s" by %ddeg' % (image.filename, degrees))
            image = copy_filename(image.transpose(mode), image)
        if flip is not None:
            mode, direction = flip
            click.echo('Flip "%s" %s' % (image.filename, direction))
            image = copy_filename(image.transpose(mode), image)
        yield image


@cli.command('blur')
@click.option('-r', '--radius', default=2, show_default=True,
              help='The blur radius.')
@processor
def blur_cmd(images, radius):
    """Applies gaussian blur."""
    blur = ImageFilter.GaussianBlur(radius)
    for image in images:
        click.echo('Blurring "%s" by %dpx' % (image.filename, radius))
        yield copy_filename(image.filter(blur), image)


@cli.command('smoothen')
@click.option('-i', '--iterations', default=1, show_default=True,
              help='How many iterations of the smoothen filter to run.')
@processor
def smoothen_cmd(images, iterations):
    """Applies a smoothening filter."""
    for image in images:
        click.echo('Smoothening "%s" %d time%s' %
                   (image.filename, iterations, iterations != 1 and 's' or '',))
        for x in xrange(iterations):
            image = copy_filename(image.filter(ImageFilter.BLUR), image)
        yield image


@cli.command('emboss')
@processor
def emboss_cmd(images):
    """Embosses an image."""
    for image in images:
        click.echo('Embossing "%s"' % image.filename)
        yield copy_filename(image.filter(ImageFilter.EMBOSS), image)


@cli.command('sharpen')
@click.option('-f', '--factor', default=2.0,
              help='Sharpens the image.', show_default=True)
@processor
def sharpen_cmd(images, factor):
    """Sharpens an image."""
    for image in images:
        click.echo('Sharpen "%s" by %f' % (image.filename, factor))
        enhancer = ImageEnhance.Sharpness(image)
        yield copy_filename(enhancer.enhance(max(1.0, factor)), image)


@cli.command('paste')
@click.option('-l', '--left', default=0, help='Offset from left.')
@click.option('-r', '--right', default=0, help='Offset from right.')
@processor
def paste_cmd(images, left, right):
    """Pastes the second image on the first image and leaves the rest
    unchanged.
    """
    imageiter = iter(images)
    image = next(imageiter, None)
    to_paste = next(imageiter, None)

    if to_paste is None:
        if image is not None:
            yield image
        return

    click.echo('Paste "%s" on "%s"' %
               (to_paste.filename, image.filename))
    mask = None
    if to_paste.mode == 'RGBA' or 'transparency' in to_paste.info:
        mask = to_paste
    image.paste(to_paste, (left, right), mask)
    image.filename += '+' + to_paste.filename
    yield image

    for image in imageiter:
        yield image
